Renal Tubular Transport of Proline, Hydroxyproline, and Glycine in Health and in Familial Hyperprolinemia *
Year: 1964
Type: article
Abstract: In man (2) and other mammals (3), most of the amino acid load in the glomerular filtrate is reabsorbed from the proximal tubule against a chemical gradient (4, 5).There are indications that human tubular absorption of the different chemical groups of amino acids occurs by means of several transport mechanisms.In cystinuria, for example, transport of only the di-amino acids, cystine, lysine, ornithine, and arginine, is im- paired (6-9).In familial glycinuria (10) only glycine reabsorption is abnormal.In Hartnup disease (11, 12) there is impaired transport of most of the neutral amino acids; there is, however, relatively little impairment in absorption of the cystinuric group of amino acids or of the imino acids and glycine.The presence, in patients with familial hyperprolinemia (13, 14), of a specific hyperaminoaciduria comprising proline, hydroxyproline, and glycine raised the possibility of a transport mech- anism selective for these three compounds.In this disease we observed that prolinuria occurred only when the plasma proline concentration was greater than 0.8 mM (normal, < 0.3 mM); at this point hydroxyprolinuria and increased glycine excretion also appeared despite normal plasma concentrations of the latter two compounds.Pre- sumably under these circumstances, the amount of proline in the glomerular filtrate exceeded its ca- *
DOI: 10.1172/jci104922
Language: English
Subfield: Biochemistry
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W2102791950